1. Field of the Invention
This invention relates to an image recorder, such as a flat-bed type color scanner, for recording an image to be reproduced onto a photosensitive material sheet. In the image recorder, a photosensitive material is drawn out of a roll of photosensitive material, and then is fed in the feed scanning direction while being scanned by a laser beam in the primary scanning direction, which is approximately perpendicular to the feed scanning direction, whereby the image is recorded onto the photosensitive material.
2. Description of the Prior Art
In an image recorder of this type, a long photosensitive film (hereinafter referred as a "film") is stored in the form of a roll and is accommodated within a film case. A film drawn out of the film case is held between a main roller and nip rollers. The film is fed in the feed scanning direction as the main roller rotates. The image recorder comprises an expose-scanning unit. The expose-scanning unit sweeps a laser beam across a film in the primary scanning direction in synchronism with a feeding of the film in the feed scanning direction thereby to record an image onto the film. The recorded film is further fed by a desired length in the feed scanning direction, and thereafter automatically cut off by a cutter located in the image recorder. Thus, a desirable length film sheet with the image reproduced thereon is obtained.
As well known in the art, stable and smooth feeding of the film in the feed scanning direction is indispensable for recording an excellent quality image. In the image recorder as above, the film is fed from the film case as the main roller rotates while being held by a pair of introduction rollers. This causes the film to be in tension in the reverse direction to the feed scanning direction and hence to slip between the main roller and the nip rollers, often resulting in unstable feeds. Force required to draw the film out of the roll, in particular, changes according to amount of remaining film in the roll. Thus, changes in amount of the remaining film exert influence on the feeding of the film.
Various techiques have been proposed to overcome the problem described above, one of them being an image recorder of Japanese Patent Laid-Open Gazette No. 63-71061.
FIG. 1 is a sectional view of a conventional image recorder. The conventional image recorder includes a pair of introduction rollers 101. The introduction rollers hold a leading edge portion of a film drawn out of a roll 105. A film 103 is drawn out of the roll 105 as the introduction rollers rotate. A main roller 102 rotates while holding the film 103 in cooperation with nip rollers 106, whereby the film 103 is fed in the feed scanning direction. A laser beam 104 scans the advancing film 103 in the primary scanning direction, the scanning being synchronized with the feeding of the film 103. Hence, an image is reproduced on the film 103. In this image recorder, the film 103 is loosened between the introduction rollers 101 and the main roller 102 while a leading edge portion 103a of the exposed film 103 being downwardly pulled. This protects the film 103 from undersirable tension which causes the film 103 to slip on the main roller 102. Consequently, image recording is attained which is free from slippage of the film 103 on the main roller 102 as described above.
After the image recording, the main roller 102 rotates couter-clockwise to rewind the exposed film 103. The main roller 102 once again rotates, this time in the clockwise direction, thereby to allow the film 103 to advance a desired distance toward a cutter 107 and guide rollers 108, so that the cutter 107 cuts off the film 103. A film sheet thus obtained has a desirable length and a reproduced image recorded thereon.
Yet, there arise several other problems as follows: While the film is fed backward, the film tends to be folded between the main roller 102 and either the introduction rollers 101 or a film case 105a, so that an unexpected loop is formed. In order to overcome this problem, the conventional image recorder employs a guiding unit 109 for preventing the film 103 from forming a loop. The image recorder also employs a switching unit for changing the feed direction. The switching unit changes the feed direction of the film 103 toward a downward direction or toward a direction to the cutter 107. In addition, since the film 103 must be fed backward after being exposed, time required for obtaining one film sheet, or a cycle time, becomes long. This will eventually deteriorate the production efficiency of the image recorder.